Thank you for letting me know about this! I've looked for a GG code like this in the past and wasn't able to locate one. I appreciate it.
I've briefly looked for existing codes and couldn't find much either... so I made one myself!

It does seem to make the game a little more fun.
And since I found the steering a bit frustrating, I looked into it and found how to alter it:
For Slalom (U).nes
- Increase the value of $B2B1 and $B2BB (up to #$3F) to reduce the inertia when you release the left/right button.
This can make the game a lot easier.
- Increase the value of $B2C7, $B2D2, $B2DC and $B2E7 (up to #$3F) for faster steering.
This too can make the game a lot easier.
Converted to Game Genie codes:
Reduce inertia (to the max)
YULLPX
YULULX
Faster steering (to the max)
YUGLYX
YUILZX
YUIUGX
YUTLYX
TBH, these codes make the game so much easier that it almost kills the fun, but they can be altered to lessen their effect.